I agree & disagree with some of the above posts. I own a Jem77BRMR, an RG350DX, A Parker Nitefly, an RGR321EXFM, and a few other axes as well. Surprisingly, the guitar I use most is the RGR321EXFM. I installed DiMarzio Breed neck & bridge pickups in it & it sounds awesome through my HD500, Blackstar HT-5 or my Carvin V3.
If this is your first step up from an entry level guitar, the RG350 isn't a bad guitar. The tremolo has mixed reviews, but I could beat the bag out of mine with zero issues. I will agree that it is the least of all Ibanez locking trems.
I'd say, unless you're hellbent on a tremolo, I'd consider a fixed bridge RG, as you can change tunings easily, and if you break a string while playing your entire guitar won't go wildly out of tune.
Also, any stock Ibanez pickups are not that great unless you spend over $1500 on the guitar. That goes for the whole range of guitars they make.
I'd consider this: I got a mahogany bodied RG on eBay for $300, and installed two DiMarzio pickups for $140. Sounds about as good as my Jem, and if I bump it by accident, I won't cry.
If you insist on a tremolo equipped guitar, I'd consider this:
It's not an RG, but it's got 24 frets and a great
tremolo system. It's $500 new, and you could wait down the road for a pickup change which, as I stated above, will do wonders
for the guitar. It's a nice, mahogany bodied guitar (as is the RG I got used on eBay), but there's not alot of used 24 fret S series out there yet.
I, personally, would consider that with a $500 budget, the two options above are better than the RG350 option. If you still have your heart set on one, I'd go used, as they sell for around $350 on eBay, and you can upgrade the pickups, at least the humbuckers, with the spare money.
Just my $1.34 worth...